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- Title
- Performance assessment for a multi-tier cellular network with alpha-stable interference.
- Creator
- Mukasa, Constantine, Aalo, Valentine A., Graduate College
- Abstract/Description
-
In wireless systems such as cellular systems, frequency reuse is employed to extend the coverage area but this process introduces undesirable co-channel interference. A tradeoff must be made between increasing system capacity and transmission quality when planning, designing and deploying such wireless systems. In order to meet the explosive demand for high data rate wireless services for a growing population within a given geographical area, future wireless cellular networks will adopt...
Show moreIn wireless systems such as cellular systems, frequency reuse is employed to extend the coverage area but this process introduces undesirable co-channel interference. A tradeoff must be made between increasing system capacity and transmission quality when planning, designing and deploying such wireless systems. In order to meet the explosive demand for high data rate wireless services for a growing population within a given geographical area, future wireless cellular networks will adopt smaller cells, such as femtocells, that are serviced by low-power base stations. As the deployment of femto-cellular base stations rapidly increases in the coming years, interference coordination and management will be the primary challenge in such heterogeneous networks. In this work, we derive a novel closed form expression for the cumulative distribution function CDF and coverage probability for a small cell wireless network operating in a Nakagami fading environment in the presence of Gaussian noise and impulsive interference modeled as an alpha-stable process. With these results, we can determine the probabilistic access thresholds that provide the best probable tradeoff between system capacity and network quality.
Show less - Date Issued
- 2014
- PURL
- http://purl.flvc.org/fau/fd/FA00005840
- Format
- Document (PDF)
- Title
- Detection of direct-sequence spread-spectrum signals in a multipath fading environment.
- Creator
- Jodoin, Claude., Florida Atlantic University, Aalo, Valentine A.
- Abstract/Description
-
In this thesis, we study the effect of Rice fading on the performance of Global Positioning System (GPS) receivers. The field-theoretic foundation of pseudo-random-noise (PRN) codes, their implementation, and their use in generating unique navigation messages in the GPS receiver is reviewed. The processing of the spread-spectrum signals within the digital delay locked loop (DDLL) in the receiver is also considered. In particular, we derive numerical expressions that can be easily evaluated...
Show moreIn this thesis, we study the effect of Rice fading on the performance of Global Positioning System (GPS) receivers. The field-theoretic foundation of pseudo-random-noise (PRN) codes, their implementation, and their use in generating unique navigation messages in the GPS receiver is reviewed. The processing of the spread-spectrum signals within the digital delay locked loop (DDLL) in the receiver is also considered. In particular, we derive numerical expressions that can be easily evaluated for the probability error and the mean-time to lose-lock, for a DDL operating in an additive white gaussian noise (AWGN) channel in the presence of Rice fading. The results obtained generalize results in the literature for the Rayleigh fading environment.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/15712
- Subject Headings
- Global Positioning System, Radio--Transmitters and transmission--Fading, Spread spectrum communications
- Format
- Document (PDF)
- Title
- Performance analysis of multi-base station slotted ALOHA for wireless LAN in a Nakagami fading environment.
- Creator
- Chopra, Anju S., Florida Atlantic University, Aalo, Valentine A.
- Abstract/Description
-
Capture effect has shown considerable improvement on performance of slotted ALOHA systems. Further, improvement is expected by increasing the number of base stations. The performance of such slotted ALOHA systems is analyzed with the aid of Equilibrium point analysis. Packet dropping due to finite number of retransmissions is taken into account. The numerical results indicate that the finite number of retransmission trials mainly contribute to the improvement of the packet dropping...
Show moreCapture effect has shown considerable improvement on performance of slotted ALOHA systems. Further, improvement is expected by increasing the number of base stations. The performance of such slotted ALOHA systems is analyzed with the aid of Equilibrium point analysis. Packet dropping due to finite number of retransmissions is taken into account. The numerical results indicate that the finite number of retransmission trials mainly contribute to the improvement of the packet dropping probability in the range of light input traffic. The use of multiple base stations improves the overall throughput and the average transmission delay in the range of heavy input traffic.
Show less - Date Issued
- 1996
- PURL
- http://purl.flvc.org/fcla/dt/15268
- Subject Headings
- Local area networks (Computer networks), Wireless communication systems, Packet switching (Data transmission), Computer network protocols
- Format
- Document (PDF)
- Title
- Performance evaluation of a DS/CDMA packet transmission system under Rician fading channel conditions.
- Creator
- Argyrides, Christodoulos., Florida Atlantic University, Aalo, Valentine A.
- Abstract/Description
-
This thesis is concerned with the performance analysis of a DS/CDMA packet radio system under Rician fading channel conditions. Analytic expressions are derived for the probability density functions and cumulative distribution functions of the total signal-to-interference ratio when considering mixed-type of interference sources. The users are divided into two groups: those that apply closed-loop power control and those that apply open-loop power control. Four different scenarios of power...
Show moreThis thesis is concerned with the performance analysis of a DS/CDMA packet radio system under Rician fading channel conditions. Analytic expressions are derived for the probability density functions and cumulative distribution functions of the total signal-to-interference ratio when considering mixed-type of interference sources. The users are divided into two groups: those that apply closed-loop power control and those that apply open-loop power control. Four different scenarios of power control were studied. The outage probability is evaluated for the four different cases of power control. A packet transmission protocol with forward error correction capabilities is considered, and the probability density functions of the signal-to-interference ratio are used to calculate the average block error probability as well as the outage probability of the system.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/12825
- Subject Headings
- Code division multiple access, Packet switching (Data transmission)
- Format
- Document (PDF)
- Title
- Matched filter bound for frequency-selective Nakagami fading channel.
- Creator
- Jiao, Jiemei., Florida Atlantic University, Aalo, Valentine A.
- Abstract/Description
-
Based on the theoretical method developed by Clark and Greenstein for frequency-selective Rayleigh fading channel, we develop a general model for frequency-selective Nakagami fading channel. We derive analytical expressions of the average bit-error-rate in an ideal space diversity mobile radio receiver using the matched filter bound. Our simulation results show that the influences of the diversity order, the shape of the multipath delay profile, and delay spread of the multipath delay profile...
Show moreBased on the theoretical method developed by Clark and Greenstein for frequency-selective Rayleigh fading channel, we develop a general model for frequency-selective Nakagami fading channel. We derive analytical expressions of the average bit-error-rate in an ideal space diversity mobile radio receiver using the matched filter bound. Our simulation results show that the influences of the diversity order, the shape of the multipath delay profile, and delay spread of the multipath delay profile. Five shapes are considered in our simulation. Our simulation results highlight the importance of the ratio the normalized delay spread d. The results show that the delay profile is of no importance for $d<0.3,$ but can have a profound influence for $d\geq0.3.$
Show less - Date Issued
- 1995
- PURL
- http://purl.flvc.org/fcla/dt/15223
- Subject Headings
- Digital communications, Signal processing--Digital techniques, Radio--Transmitters and transmission--Fading
- Format
- Document (PDF)
- Title
- Effect of Correlated Non-Gaussian Quadratures on the Performance of Binary Modulations.
- Creator
- Aalo, Valentine A., Efthymoglou, George P.
- Date Issued
- 2011
- PURL
- http://purl.flvc.org/fau/flvc_fau_islandoraimporter_10.1155_2011_176486_1628608975
- Format
- Citation
- Title
- On the Error Rate Analysis of Dual-Hop Amplify-and-Forward Relaying in Generalized- K Fading Channels.
- Creator
- Efthymoglou, George P., Bissias, Nikolaos, Aalo, Valentine A.
- Date Issued
- 2010
- PURL
- http://purl.flvc.org/fau/flvc_fau_islandoraimporter_10.1155_2010_584594_1628173989
- Format
- Citation
- Title
- Physical Layer Security of Wireless Transmissions Over Fading Channels.
- Creator
- Blanc, Sadrac, Aalo, Valentine A., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The open nature of the wireless medium makes the wireless communication susceptible to eavesdropping attacks. In addition, fading and shadowing significantly degrade the performance of the communication system in the wireless networks. A versatile approach to circumvent the issues of eavesdropping attacks while exploiting the physical properties of the wireless channel is the so-called physical layer-security. In this work, we consider a model in which two legitimate users communicate in the...
Show moreThe open nature of the wireless medium makes the wireless communication susceptible to eavesdropping attacks. In addition, fading and shadowing significantly degrade the performance of the communication system in the wireless networks. A versatile approach to circumvent the issues of eavesdropping attacks while exploiting the physical properties of the wireless channel is the so-called physical layer-security. In this work, we consider a model in which two legitimate users communicate in the presence of an eavesdropper. We investigate the performance of the wireless network at the physical layer that is subject to a variety of fading environments that may be modeled by the Rayleigh, Nakagami-m, and Generalized-K distributions, to mention a few. We use the secrecy outage probability (SOP) as the standard performance metrics to study the performance of the wireless networks. We propose two different approaches to compute the secrecy outage probability, and derive explicit expressions for the secrecy outage probability that allow us to characterize the performance of the wireless networks. Specifically, we use a direct integration approach as well as a Taylor series base approach to evaluate the secrecy outage probability. Finally, we use computer simulations, based on MATLAB, to confirm the analytical results.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004729, http://purl.flvc.org/fau/fd/FA00004729
- Subject Headings
- Data encryption (Computer science), Digital communications -- Reliability -- Mathematics, Internetworking (Telecommunication), Radio wave propagation, Wireless communication systems -- Security measures
- Format
- Document (PDF)
- Title
- A Study on Random Sum Statistics: Application to Wireless Network Performance Analysis.
- Creator
- Pattaramalai, Suwat, Aalo, Valentine A., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The statistics of random sum is studied and used to evaluate performance metrics in wireless networks. Pertinent wireless network performance measures such as call completion/dropping probabilities and the average number of handovers usually require the probability distributions of the cell dwell time and call holding time; and are therefore not easy to evaluate. The proposed performance evaluation technique requires the moments of the cell dwell time and is given in terms of the Laplace...
Show moreThe statistics of random sum is studied and used to evaluate performance metrics in wireless networks. Pertinent wireless network performance measures such as call completion/dropping probabilities and the average number of handovers usually require the probability distributions of the cell dwell time and call holding time; and are therefore not easy to evaluate. The proposed performance evaluation technique requires the moments of the cell dwell time and is given in terms of the Laplace transform function of the call holding time. Multimedia services that have Weibull and generalized gamma distributed call holding times are investigated. The proposed approximation method uses the compound geometric random sum distribution and requires that the geometric parameter be very small. For applications in which this parameter is not sufficiently small, a result is derived that improves the accuracy (to order of the geometric parameter) of the performance measures evaluated.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FA00012575
- Subject Headings
- Mobile communication systems--Technological innovations, Computer network protocols, Local area networks (Computer networks), Differentiable dynamical systems
- Format
- Document (PDF)
- Title
- Stochastic Modeling of Wireless Communications in a Fading Environment via Fox's H-Function.
- Creator
- Mukasa, Constantine, Aalo, Valentine A., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
In wireless communications systems, it is well known that the instantaneous received signal is a random variable that follows a given distribution. The randomness mainly stems from e ects such as multipath fading, shadowing, and interference. The received signal is a relevant metric, such that several distributions have been used in the literature to characterize it. However, as new radio technologies emerge, the known distributions are deemed insu cient to t simulated and measure data....
Show moreIn wireless communications systems, it is well known that the instantaneous received signal is a random variable that follows a given distribution. The randomness mainly stems from e ects such as multipath fading, shadowing, and interference. The received signal is a relevant metric, such that several distributions have been used in the literature to characterize it. However, as new radio technologies emerge, the known distributions are deemed insu cient to t simulated and measure data. Subsequently, as the wireless industry moves onto the fth generation (5G), newer distributions are proposed to well represent the received signal for new wireless technologies, including those operating in the millimeter-wave (mmWave) band. These are mainly application speci c and may not be adequate to model complex 5G devices performance. Therefore, there is a need to unify and generalize the received signal distributions used for performance analysis of wireless systems. Secondly, an explosion of new radio technologies and devices operating in the same limited radio spectrum to collect and share data at alarming rates is expected. Such an explosion coupled with the 5G promise of ubiquitous connectivity and network densi cation, will thrust interference modeling in dense networks to the fore-front. Thus, interference characterization is essential when analyzing such wireless networks. Thirdly, the classical distributions used to model the received signal do not account for the inherent mobility feature for emerging radio technologies, such as avionics systems (e.g. drones), which may make the distributions inadequate as mobility e ects can no longer be ignored. Consequently, in this dissertation, we propose the use of a unifying distribution, the Fox's H-function distribution, with subsume ability to represent several traditional and future distributions, as a statistical tool to evaluate the performance of wireless communications systems. Additionally, two interference models, one with a xed number and the other with a random number of interferers, are considered to derive interference statistics, and further utilize the results to analyze system performance under the e ect of interference. Finally, we extend the classical distributions to include the mobility regime for several wireless network topologies, and perform network analysis. The analytical results are validated using computer Monte Carlo simulations.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00005934
- Subject Headings
- Dissertations, Academic -- Florida Atlantic University, Wireless communications systems., Stochastic modeling., H-functions.
- Format
- Document (PDF)
- Title
- Statistical and Entropy Considerations for Ultrasound Tissue Characterization.
- Creator
- Navumenka, Khrystsina, Aalo, Valentine A., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
Modern cancerous tumor diagnostics is nearly impossible without invasive methods, such as biopsy, that may require involved surgical procedures. In recent years some work has been done to develop alternative non-invasive methods of medical diagnostics. For this purpose, the data obtained from an ultrasound image of the body crosssection, has been analyzed using statistical models, including Rayleigh, Rice, Nakagami, and K statistical distributions. The homodyned-K (H-K) distribution has been...
Show moreModern cancerous tumor diagnostics is nearly impossible without invasive methods, such as biopsy, that may require involved surgical procedures. In recent years some work has been done to develop alternative non-invasive methods of medical diagnostics. For this purpose, the data obtained from an ultrasound image of the body crosssection, has been analyzed using statistical models, including Rayleigh, Rice, Nakagami, and K statistical distributions. The homodyned-K (H-K) distribution has been found to be a good statistical tool to analyze the envelope and/or the intensity of backscattered signal in ultrasound tissue characterization. However, its use has usually been limited due to the fact that its probability density function (PDF) is not available in closed-form. In this work we present a novel closed-form representation for the H-K distribution. In addition, we propose using the first order approximation of the H-K distribution, the I-K distribution that has a closed-form, for the ultrasound tissue characterization applications. More specifically, we show that some tissue conditions that cause the backscattered signal to have low effective density values, can be successfully modeled by the I-K PDF. We introduce the concept of using H-K PDF-based and I-K PDF-based entropies as additional tools for characterization of ultrasonic breast tissue images. The entropy may be used as a goodness of fit measure that allows to select a better-fitting statistical model for a specific data set. In addition, the values of the entropies as well as the values of the statistical distribution parameters, allow for more accurate classification of tumors.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004922, http://purl.flvc.org/fau/fd/FA00004922
- Subject Headings
- Ultrasonics in medicine., Artificial intelligence., Computer vision in medicine., Diagnostic ultrasonic imaging., Bioinformatics.
- Format
- Document (PDF)
- Title
- Performance studies on digital cellular radio systems operating in a non-Gaussian multipath fading environment.
- Creator
- Chayawan, Chirasil., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
This dissertation is concerned with studies on the performance aspects of digital cellular radio systems operating in non-Gaussian multipath fading environments. The multipath fading channel, modeled as a superposition of sinusoidal random vectors, is the main focus of this work. Elementary phase distributions, which cause quadrature components of the composite received vector to be correlated, are studied and relevant envelope distribution for the resulting non-Gaussian quadrature components...
Show moreThis dissertation is concerned with studies on the performance aspects of digital cellular radio systems operating in non-Gaussian multipath fading environments. The multipath fading channel, modeled as a superposition of sinusoidal random vectors, is the main focus of this work. Elementary phase distributions, which cause quadrature components of the composite received vector to be correlated, are studied and relevant envelope distribution for the resulting non-Gaussian quadrature components is investigated. The Student-t distributed random process is chosen to model the quadrature components in an indoor multipath fading channel when the number of sinusoidal random vectors is small. For the correlated bivariate non-Gaussian quadrature components, the exact probability distribution function, corresponding to those elementary phase distributions as well as the Gaussian approximation for resultant envelope are evaluated. The scenario where the elementary envelope is beta distributed is also considered. Spherically invariant random process (SIRP) is also used to model the multipath fading channel. The performance analysis based on the spherically invariant multipath fading channel, is then evaluated. The system performance, specified in terms of outage probability and average error probability, significantly depends on the choice of characteristic probability distribution function of the random process that describes the RF ambient. It is shown that the optimality of the optimum combining and maximal ratio combining schemes in interference-limited environments is still retained under the spherically invariant multipath fading channel model.
Show less - Date Issued
- 2002
- PURL
- http://purl.flvc.org/fau/fd/FADT12011
- Subject Headings
- Cellular telephone systems, Digital communications, Radio--Transmitters and transmission--Fading, Gaussian processes
- Format
- Document (PDF)
- Title
- Performance analysis of mobile LEO satellite cellular systems.
- Creator
- Alwakeel, Mohammed., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
This dissertation is concerned with studies on the performance aspects of mobile LEO satellite cellular systems. Relevant performance measures studied in the dissertation include new call blocking probability, handoff failure probability, call termination probability, and call dropping probability. The analytical teletraffic models available in the literature are generalized in this work in order to characterize the 3G systems more realistically. The effect of earth rotation on cell residence...
Show moreThis dissertation is concerned with studies on the performance aspects of mobile LEO satellite cellular systems. Relevant performance measures studied in the dissertation include new call blocking probability, handoff failure probability, call termination probability, and call dropping probability. The analytical teletraffic models available in the literature are generalized in this work in order to characterize the 3G systems more realistically. The effect of earth rotation on cell residence time is also investigated and a new cell residence time model is developed. The new model proposed uses right-truncated gamma distribution to describe the statistics of residence time in the origination cell; and, the generalized beta distribution is used to model the residence time in subsequent cells. A closed-form expression to determine the premature call termination and call dropping probabilities is proposed. The proposed expression requires only the cumulative distribution function of the call holding time and the first four moments of the cell residence time. In all the above probabilistic considerations, the arrival process is regarded as: (i) Poissonian implying voice-like traffic and (ii) non-Poissonian depicting inhomogeneous mix of voice, data, and video transmissions expected on a trunk traffic. The effect of factors that may affect the signal intensity on the performance of mobile LEO satellite cellular systems is also investigated. In particular, a mathematically tractable expression to approximate the moments of cell residence time in origination cell as well as in subsequent cells is developed based on the received signal power.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/12132
- Subject Headings
- Wireless communication systems, Personal communication service systems, Artificial satellites in telecommunication, Mobile communication systems
- Format
- Document (PDF)
- Title
- Performance analysis of linear diversity schemes in generalized gamma fading channels.
- Creator
- Piboongungon, Terawat., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The main focus of this dissertation is to analyze the performance of linear diversity schemes operating in generalized gamma fading channels. The generalized gamma fading model is a versatile fading envelope that generalizes many of commonly used statistical models that describe signal fluctuations due to multipath, shadowing, or a mixture of such processes. The traditional linear diversity combining techniques such as maximal ratio combining (MRC), equal gain combining (EGC), and selection...
Show moreThe main focus of this dissertation is to analyze the performance of linear diversity schemes operating in generalized gamma fading channels. The generalized gamma fading model is a versatile fading envelope that generalizes many of commonly used statistical models that describe signal fluctuations due to multipath, shadowing, or a mixture of such processes. The traditional linear diversity combining techniques such as maximal ratio combining (MRC), equal gain combining (EGC), and selection combining (SC) are addressed with reference to generalized gamma fading environments. For the special case of Nakagami fading, new expressions for outage probability and error-rate performance of linear diversity schemes with arbitrary fading parameters are derived in terms of the Lauricella function. Effects of correlated fading are also studied. Their fruitful application to third generation (3G) wideband code division multiple access (WCDMA) systems, particularly for multiple-input multiple-output (MIMO) and 2D-RAKE receivers are demonstrated. The results exhibit a finite integral representation that can be used for fast and accurate numerical computation. A detail study is also done on multivariate generalized gamma fading environments. Relevant statistical characterization of the sum of independent generalized gamma random variables is derived and expressed in terms of the multivariable Fox's H-function. Since numerical evaluation for the multivariate Fox's H-function is difficult, simpler numerical computations are developed using moment generating function and characteristic function approaches. Since some wireless applications may not have enough space among diversity branches, the statistical characterizations of multivariate correlated generalized gamma fading are relevant in such cases. An investigation on the outage performance for multi-branch selection combining is performed for the correlated multivariate generalized gamma channel. Finally, the dissertation summarizes the main results and explores some directions for further studies.
Show less - Date Issued
- 2005
- PURL
- http://purl.flvc.org/fcla/dt/12135
- Subject Headings
- Numerical integration, Wireless communication systems--Mathematical models, Frequency spectra--Mathematical models
- Format
- Document (PDF)
- Title
- Performance analysis of wireless communication systems in multipath fading environments with correlated shadowing and co-channel interference.
- Creator
- Zhang, Jingjun., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The performance aspects of conventional cellular (FDMA/TDMA) and CDMA systems with micro- and macroscopic diversity reception are investigated in a severe mobile communication environment which is characterized by path loss, correlated lognormal shadowing, multipath fading, background noise and interference. Under a co-channel interference-limited assumption, an exact analytical expression for the co-channel interference (CCI) probability is presented for a macroscopic diversity system with...
Show moreThe performance aspects of conventional cellular (FDMA/TDMA) and CDMA systems with micro- and macroscopic diversity reception are investigated in a severe mobile communication environment which is characterized by path loss, correlated lognormal shadowing, multipath fading, background noise and interference. Under a co-channel interference-limited assumption, an exact analytical expression for the co-channel interference (CCI) probability is presented for a macroscopic diversity system with an arbitrary number of correlated macroscopic branches. For noise-limited systems, the average bit-error-rate (BER) and outage probability performances of a narrowband mobile communication system with micro- and macrodiversity reception are evaluated. In the relevant analysis, both Nakagami and Rician fading channels are considered. When both co-channel interference and noise coexists, the results for a Nakagami fading channel show that diversity reception can be used to reduce the effects of interference while combating fading and shadowing. Micro- and macroscopic diversities are also applied to a multicell DS-CDMA system. In a conventional cellular system with macroscopic diversity, the mobile user is usually connected to the closest base station. However, a base-station selection scheme based on a least attenuation criterion is shown to provide a significant performance improvement over the conventional system. In this case, the system performance is examined in terms of BER and outage probability, while accounting for the effects of path loss, correlated shadowing, multipath fading, multiple access interference, and imperfect power control.
Show less - Date Issued
- 1999
- PURL
- http://purl.flvc.org/fcla/dt/12600
- Subject Headings
- Wireless communication systems, Code division multiple access
- Format
- Document (PDF)
- Title
- System Level Modeling and Simulation with MLDesigner.
- Creator
- Kovalski, Fabiano, Aalo, Valentine A., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
System modeling has the potential to enhance system design productivity by providing a platform for system performance evaluations. This model must be designed at an abstract level, hiding system details. However, it must represent any subsystem or its components at any level of specification details. In order to model such a system, we will need to combine various models-of-computation (MOC). MOC provide a framework to model various algorithms and activities, while accounting for and...
Show moreSystem modeling has the potential to enhance system design productivity by providing a platform for system performance evaluations. This model must be designed at an abstract level, hiding system details. However, it must represent any subsystem or its components at any level of specification details. In order to model such a system, we will need to combine various models-of-computation (MOC). MOC provide a framework to model various algorithms and activities, while accounting for and exploiting concurrency and synchronization aspects. Along with supporting various MOC, a modeling environment should also support a well developed library. In this thesis, we have explored various modeling environments. MLDesigner (MLD) is one such modeling environment that supports a well developed library and integrates various MOC. We present an overview and discuss the process of system modeling with MLD. We further present an abstract model of a Network-on-Chip in MLD and show latency results for various customizable parameters for this model.
Show less - Date Issued
- 2006
- PURL
- http://purl.flvc.org/fau/fd/FA00012531
- Subject Headings
- High performance computing, Electronic data processing--Distributed processing, Information technology--Management, Spatial analysis (Statistics), System design
- Format
- Document (PDF)
- Title
- Performance Analysis of Spectrum Sensing Schemes Based on Fractional Lower Order Moments for Cognitive Radios in Alpha- Stable Noise Environments.
- Creator
- Ackie, A-Bon Elfick, Aalo, Valentine A., Florida Atlantic University, College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
Natural and manmade noise signals tend to exhibit impulsive behaviors. Therefore modeling those signals as α-stable processes is better suited towards the development of a practical spectrum sensing scheme. However, the performances of detectors operating in an α-stable noise environment are difficult to evaluate. This is because an α-stable random variable can usually only be modeled by the characteristic function since closed-form expressions are usually not available except for the special...
Show moreNatural and manmade noise signals tend to exhibit impulsive behaviors. Therefore modeling those signals as α-stable processes is better suited towards the development of a practical spectrum sensing scheme. However, the performances of detectors operating in an α-stable noise environment are difficult to evaluate. This is because an α-stable random variable can usually only be modeled by the characteristic function since closed-form expressions are usually not available except for the special values of the characteristic exponent that correspond to the Cauchy and Gaussian noise distributions. In this thesis, we derive a general closed-form expression for the probability density function (PDF) of symmetric alpha stable processes having rational characteristic exponent (0<α≤2). Consequently, we obtain analytical expressions for the PDF and corresponding complementary cumulative distribution function (CCDF) of the proposed fractional lower order moment (FLOM) detector. Utilizing false alarm and detection probabilities, the performance analysis of the proposed spectrum sensing scheme is conducted with the assumption that the cognitive radio (CR) users are operating in non-fading channels. We validate the analytical results with Monte Carlo simulations. The effect of the distribution parameters on the receiver operating characteristic (ROC) curves is verified.
Show less - Date Issued
- 2016
- PURL
- http://purl.flvc.org/fau/fd/FA00004561, http://purl.flvc.org/fau/fd/FA00004561
- Subject Headings
- Cognitive radio networks., Radio frequency allocation., Radio resource management (Wireless communications), Wireless communication systems.
- Format
- Document (PDF)
- Title
- Blind source separation using a spatial fourth-order cumulant matrix-pencil.
- Creator
- Dishman, John Fitzgerald., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
-
The research presented investigates the use of cumulants in conjunction with a spectral estimation technique of the signal subspace to perform the blind separation of statistically independent signals with low signal-to-noise ratios under a narrowband assumption. A new blind source separation (BSS) algorithm is developed that makes use of the generalized eigen analysis of a matrix pencil defined on two similar spatial fourth-order cumulant matrices. The algorithm works in the presence of...
Show moreThe research presented investigates the use of cumulants in conjunction with a spectral estimation technique of the signal subspace to perform the blind separation of statistically independent signals with low signal-to-noise ratios under a narrowband assumption. A new blind source separation (BSS) algorithm is developed that makes use of the generalized eigen analysis of a matrix pencil defined on two similar spatial fourth-order cumulant matrices. The algorithm works in the presence of spatially and/or temporally correlated noise and, unlike most existing higher-order BSS techniques, is based on a spectral estimation technique rather than a closed loop optimization of a contrast function, for which the convergence is often problematic. The dissertation makes several contributions to the area of blind source separation. These include: (1) Development of a robust blind source separation technique that is based on higher-order cumulant based principle component analysis that works at low signal-to-noise ratios in the presence of temporally and/or spatially correlated noise. (2) A novel definition of a spatial fourth-order cumulant matrix suited to blind source separation with non-equal gain and/or directional sensors. (3) The definition of a spatial fourth-order cumulant matrix-pencil using temporal information. (4) The concept of separation power efficiency (SPE) as a measure of the algorithm's performance. Two alternative definitions for the spatial fourth-order cumulant matrix that are found in the literature are also presented and used by the algorithm for comparison. Additionally, the research contributes the concept of wide sense equivalence between matrix-pencils to the field of matrix algebra. The algorithm's performance is verified by computer simulation using realistic digital communications signals in white noise. Random mixing matrices are generated to ensure the algorithm's performance is independent of array geometry. The computer results are promising and show that the algorithm works well down to input signal-to-noise ratios of -6 dB, and using as few as 250 x 103 samples.
Show less - Date Issued
- 2001
- PURL
- http://purl.flvc.org/fcla/dt/11963
- Subject Headings
- Matrix pencils, Adaptive signal processing, Matrices
- Format
- Document (PDF)
- Title
- Diversity techniques in direct sequence code division multiple access communication systems.
- Creator
- Ugweje, Okechukwu Clark., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
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This dissertation investigates the performance of different space diversity combining techniques for the wireless mobile communication systems employing Direct Sequence-Code Division Multiple Access (DS-CDMA). It covers two research topics, all falling under the umbrella of diversity combining techniques. The first part deals with diversity reception of wideband DS-CDMA signals in which the diversity branches experience some correlation. This analysis is performed without the usual assumption...
Show moreThis dissertation investigates the performance of different space diversity combining techniques for the wireless mobile communication systems employing Direct Sequence-Code Division Multiple Access (DS-CDMA). It covers two research topics, all falling under the umbrella of diversity combining techniques. The first part deals with diversity reception of wideband DS-CDMA signals in which the diversity branches experience some correlation. This analysis is performed without the usual assumption that diversity branches are independent and hence uncorrelated. In this case, the analysis is limited to the conventional diversity techniques such as maximal ratio combining, equal gain combining and selection diversity. In particular, the effect of correlation on system performance using two correlation profiles namely, the constant and the exponential correlation profiles is explored. In the constant correlation, the correlation between adjacent antenna are equal regardless of the separation between them, while in exponential correlation, it is assumed that the level of correlation between adjacent antennas decreases as their separation increases. The second topic deals with the development of new combining techniques. Two new techniques--the Generalized Selection Diversity Combining (GSDC) and the Maximal Ratio-Selection Diversity Combining (MR-SDC)--are introduced and analyzed in this dissertation. Analytical models which can be used to evaluate the performance of these new techniques are indicated. Results show that GSDC perform significantly better than the conventional selection diversity when two or more larger signals are selected. The MR-SDC technique accounts for the possibility of using a large array of antennas and for occasions when the receiving antennas may not be collocated. Also, it is shown that for the large array of antennas, better performance is achieved when the MR-SDC is employed with the maximum number of subgroups. The figures of merit used in this dissertation are the average Bit Error Rate (BER) and the probability of outage for a given threshold probability of error. Exact and approximate expressions are derived for the average bit error probability as well as for the outage probability while accounting for the effect of multipath fading, multiple access interference and background noise.
Show less - Date Issued
- 1997
- PURL
- http://purl.flvc.org/fcla/dt/12524
- Subject Headings
- Code division multiple access, Wireless communication systems
- Format
- Document (PDF)
- Title
- Performance study of some diversity schemes in a Nakagami fading channel.
- Creator
- Sannegowda, Ramesh Panditan., Florida Atlantic University, Aalo, Valentine A., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
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Closed form results for the symbol error probabilities are derived for M-ary, L branch Selection diversity schemes and Partial Decision combining schemes in a Nakagami fading environment using noncoherent frequency-shift keying modulation. The Maximum SNR selection, the Maximum output selection, the Optimal partial decision, and the Majority voting schemes are considered in this analysis. The analysis is not limited to integer values of the Nakagami fading parameter m. Results for the...
Show moreClosed form results for the symbol error probabilities are derived for M-ary, L branch Selection diversity schemes and Partial Decision combining schemes in a Nakagami fading environment using noncoherent frequency-shift keying modulation. The Maximum SNR selection, the Maximum output selection, the Optimal partial decision, and the Majority voting schemes are considered in this analysis. The analysis is not limited to integer values of the Nakagami fading parameter m. Results for the Rayleigh fading channel are obtained and presented as special cases of those of the Nakagami fading model. The symbol error probability when the diversity branches undergo different fading statistics with unequal mean SNR are considered for the Maximum SNR selection scheme. Outage probabilities are also calculated for some of the diversity combining schemes. A comparison of all the four schemes are discussed using the performance curves.
Show less - Date Issued
- 1994
- PURL
- http://purl.flvc.org/fcla/dt/15011
- Subject Headings
- Electromagnetic waves--Transmission, Radio--Transmitters and transmission--Fading, Radio waves--Scattering
- Format
- Document (PDF)
